Plug member and mounting and dismounting device therefor

ABSTRACT

A plug member can be mounted to the end of a pipe and removed therefrom by automated operation. 
     A mounting and dismounting device  21  for mounting and dismounting a plug member  11  with respect to an oil country tubular good P. The plug member  11  comprises an outer tube  12  having seal portions  16   a  and  16   b  and a circumferential groove  12   a,  a shuttle  13,  a cap  14,  and a shuttle biasing spring  15  secured to the cap  14  and the shuttle  13.  The mounting and dismounting device  21  comprises a tubular holding body  22,  a rod  23  which has a conical end portion  23   a  and which is disposed so as to move inside the tubular holding body  22,  and moving means  24  and  25  which allow the tubular holding body  22  and the rod  23  to independently move. The tubular holding body  22  has ball-receiving holes  22   a  into which fit balls  26  which engage with the circumferential groove  12   a.  The tubular holding body  22  is inserted into the outer tube  12  through the proximal end of the tube so as to make its tip contact the end surface of the shuttle on the side of the proximal end, and the rod  23  is moved relative to the tubular holding body  22  so as to contact its end portion  23   a  with the balls  26  to make the balls  26  engage with the circumferential groove  12   a,  thereby connecting the tubular holding body  22  and the outer tube  12.  The rod is moved relative to the tubular holding body  22  to retract the end portion  23   a,  thereby releasing the connection between the tubular holding body  22  and the outer tube  12.

TECHNICAL FIELD

This invention relates to a plug member and a mounting and dismountingdevice therefor. Specifically, the present invention relates to a plugmember which is mounted inside an end portion of a long pipe such as anoil country tubular good when carrying out thread cutting on the pipe inorder to prevent shavings and the like formed during the thread cuttingfrom entering the pipe, and a device for mounting the plug member in apipe or dismounting or removing it from a pipe.

BACKGROUND ART

FIG. 5 is an explanatory view showing thread cutting being carried outon an end of a long pipe such as an oil country tubular good. As shownin FIG. 5, during thread cutting, the vicinity of an end of a pipe Pwhich is undergoing thread cutting is rotatably supported by a chuck 1.Thread cutting is carried out by contacting the portion of the end ofthe pipe P to undergo thread cutting with a cutting tool 2 which can beadjusted in position relative to the pipe P as the pipe P is beingrotated.

During this thread cutting operation, if shavings caused by the cuttingor cutting oil enter into the rear of the interior of a long pipe suchas an oil country tubular good, the shavings are not only difficult toremove but extra effort is required for their removal. Therefore, PatentDocument 1, for example, discloses an invention which prevents shavingsor the like from entering into the interior of a pipe by mounting a plugmember in the interior of an end of the pipe prior to thread cutting.The plug member disclosed by Patent Document 1 has a seal member whichfits in a groove provided in its outer peripheral surface.

However, mounting of the plug member in an end of a pipe and removal ofthe plug member from the end of the pipe must be carried out manually.Therefore, the plug member interferes with automation of the entireprocess of performing thread cutting of a pipe, and the time requiredfor thread cutting increases.

Patent Document 2 discloses an invention in which a plug member having agroove provided in the outer peripheral surface of the body thereof ismounted in a pipe with a seal member fitted into the groove, aprojecting grip for mounting and dismounting being attached to one endsurface of the body of the plug member. According to that invention, thegrip can be grasped by a mounting and dismounting device, so mounting ofthe plug member in the end of a pipe and removal of the plug member fromthe end of a pipe can be mechanized by a plug member mounting anddismounting device.

Patent Document 1: JP H07-246504 A

Patent Document 2: JP H07-171701 A

DISCLOSURE OF INVENTION Problem Which the Invention is to Solve

In the invention disclosed in Patent Document 2, a grip projects in aplug member mounted inside a pipe towards the portion of the pipe whichis undergoing thread cutting, so shavings produced by thread cutting caneasily be wrapped around the grip. If the plug member is removed fromthe end of a pipe with a mounting and dismounting device in a state inwhich shavings are wrapped around the grip, due to the presence of theshavings, it becomes difficult for the mounting and dismounting deviceto grasp the grip with certainty, and the plug member cannot be removedusing the plug member mounting and dismounting device.

Furthermore, a mounting and dismounting device for a plug memberaccording to that invention is installed in a pocket of a turret of atool rest. Therefore, when mounting and dismounting of a plug member isperformed on an end of a pipe, it is necessary to carry out twomovements in the form of translation and rotation of the turret. As aresult, the time required for mounting of the plug member increases anda drive mechanism for the device becomes complicated.

In addition, a pocket in which a mounting and dismounting device for aplug member according to that invention is installed can no longer beused for other purposes. Furthermore, the mounting and dismountingdevice for a plug member interferes with nearby pockets, and the nearbypockets can also no longer be used.

The problem which the present invention is to solve is that a plugmember mounted in the end of a pipe for preventing shavings or the likefrom entering into the pipe cannot be removed with a mounting anddismounting device for a plug member.

Another problem which the present invention is to solve is that ifmounting and dismounting of a plug member is carried out with a mountingand dismounting device, a prolonged time is required for mounting of theplug member, and the mounting and dismounting device interferes not onlywith the pocket in which the mounting and dismounting device for a plugmember is installed but also with other nearby pockets, so the nearbypockets can no longer be used.

Means for Solving the Problem

The present invention is a plug member to be mounted in an end of a pipewhich is to undergo thread cutting,

characterized by comprising an outer tube having a proximal end and adistal end (leading end), a shuttle which is installed so as to be ableto reciprocate inside the outer tube between the proximal end and thedistal end, a cap which is mounted on the distal end of the outer tubeto close off the opening of the distal end, and a shuttle biasing springhaving one end secured to the cap and the other end secured to theshuttle,

the outer tube having a seal member which is provided on its outerperipheral surface and which forms a seal against a pipe, and acircumferential groove which is formed in its inner peripheral surfacein the proximal end portion,

the shuttle being disposed in a predetermined position inside theproximal end portion of the outer tube and preferably having a fittingportion for positioning which is formed on the end face of the shuttleon the side of its proximal end, and

the shuttle biasing spring producing a spring pressing force on theshuttle towards the proximal end when the shuttle moves from thepredetermined position towards the distal end.

From another aspect, the present invention is a plug member mounting anddismounting device for mounting the above-described plug memberaccording to the present invention in a pipe or removing it from a pipe,characterized by comprising a tubular holding body which is disposedinside the outer tube so as to be able to move with respect to the outertube in the axial direction of the outer tube, a rod which has a distalend portion with a conical shape which decreases in outer diameter fromits proximal end towards its distal end and which is disposed inside thetubular holding body so as to be able to move with respect to thetubular holding body in the axial direction of the tubular holding body,moving means for independently moving the tubular holding body and therod, and preferably a stopper which is installed forward of the plugmember having its outer tube connected to the tubular holding body andwhich by abutting thereon the end surface of a pipe on which the plugmember is mounted, can simultaneously perform alignment of the plugmember and the pipe and mounting of the plug member with respect to thepipe,

wherein the tubular holding body has ball-receiving holes in apredetermined position into which balls which can engage with thecircumferential groove of the outer tube can fit so as not to protrudeoutwards from the outer peripheral surface of the tubular holding body,and when it is inserted into the outer tube through the proximal end ofthe tube, its distal end can contact the end surface of the proximal endof the shuttle, the tubular body preferably having a fitting portionwhich is formed on its distal end portion so as to fit the fittingportion of the shuttle which is formed on its proximal end, and

the rod can make the balls protrude outwards from the outer peripheralsurface of the tubular holding body and engage with the circumferentialgroove to connect the tubular holding body and the outer tube by movingrelative to the tubular holding body so as to contact its distal endportion with the balls, and it can release the connection between thetubular holding body and the outer tube by moving relative to thetubular holding body so as to retracting its distal end portion from theballs and let the balls fit into the ball-receiving holes.

EFFECTS OF THE INVENTION

According to the present invention, because a plug member is mounted anddismounted by holding the interior of the plug member, shavings producedby thread cutting can be completely prevented from becoming wrappedaround the plug member. Therefore, not only mounting of the plug memberin the end of a pipe but also removal from the end of a pipe can bemechanized and automated by a plug member mounting and dismountingdevice.

In addition, according to the present invention, alignment of a pipe andmounting of a plug member in a pipe can be simultaneously performed.Therefore, the cycle time required for mounting and dismounting of aplug member can be shortened when considering the overall cycle time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a plug member accordingto the present invention.

FIG. 2 is a longitudinal cross-sectional view showing the main portionof a mounting and dismounting device for a plug member according to thepresent invention when a plug member according to the present inventionis connected thereto and inserted into a long pipe.

FIG. 3 is an overall view of a mounting and dismounting device for aplug member according to the present invention as viewed from the side.

FIG. 4 is a sectional view taken along line A-A of FIG. 3.

FIG. 5 is a schematic view of a conventional end portion working device.

LIST OF REFERENCE NUMERALS

-   -   11: plug member; 12: outer tube; 12 a: circumferential groove;        13: shuttle; 13 a: recess; 14: cap; 15: shuttle biasing spring;        16 a, 16 b: seal members; 21: plug member mounting and        dismounting device; 22: holding member; 22 a: ball-receiving        hole; 23: rod; 23 a: end portion; 24, 25: moving means; 26:        balls; 27: stopper

BEST MODE FOR CARRYING OUT THE INVENTION

Below, the best mode for carrying out the present invention will beexplained while referring to FIGS. 1-4. In the following explanation, anexample will be given of the case in which a pipe is an oil countrytubular good.

FIG. 1 is a longitudinal cross-sectional view of a plug member accordingto the present invention. FIG. 2 is a longitudinal cross-sectional viewshowing the main portion of a mounting and dismounting device for a plugmember according to the present invention when it is connected to a plugmember according to the present invention and inserted into a long pipe.FIG. 3 is an overall view of a mounting and dismounting device for aplug member according to the invention as viewed from the side. FIG. 4is a sectional view taken along line A-A of FIG. 3.

In FIG. 1, 11 indicates a plug member according to the present inventionwhich is mounted inside the end of an oil country tubular good P, forexample, which is to undergo thread cutting. The plug member 11comprises an outer tube 12, a shuttle 13, a cap 14, and a shuttlebiasing spring 15.

The outer tube 12 has a proximal end (the end on the right side inFIG. 1) and a distal or leading end (the end on the left side in FIG.1). The outer tube 12 has sealing members 16 a and 16 b which are madeof hard rubber, for example, and which have a diameter slightly largerthan the inner surface of an oil country tubular good P in which theplug member is mounted on the outer peripheral surface of the tube inpositions near both ends thereof. The sealing members 16 a and 16 b aresealed against the oil country tubular good P. A circumferential groove12 a is provided on the inner peripheral surface of the outer tube 12near the proximal end (the side on which sealing member 16 a ismounted). Below-described balls 26 engage with the circumferentialgroove 12 a.

In the embodiment shown in FIG. 1, sealing member 16 a is positioned onthe outer peripheral surface of the outer tube 12 by an outwardlyextending flange of a tubular body 12 b, and sealing member 16 b ispositioned on the outer peripheral surface of the outer tube 12 by aspacer sleeve 12 c disposed between it and sealing member 16 a.

The shuttle 13 is normally disposed inside the outer tube 12 near theproximal end. The shuttle 13 can move inside the outer tube between theproximal end and the distal end (the opposite end from the proximalend). In the embodiment shown in FIG. 1, the end surface of the shuttle13 on the side of the proximal end has a recess 13 a which serves as afitting portion for positioning and which is formed in a conical shapehaving a flat top face and an inner diameter which decreases from theproximal end towards the distal end.

The cap 14 is secured by a screw to the distal end of the outer tube 12to close off the opening formed at the distal end of the outer tube 12.By securing the cap 14 with a nut 17, the sealing members 16 a and 16 bin this embodiment can be secured and positioned in the above-describedpositions.

The shuttle biasing spring 15 is disposed inside the outer tube 12 withone of its ends secured to the cap 14 and its other end secured to theshuttle 13. The shuttle biasing spring 15 biases the shuttle 13 so thatwhen the below-described plug member mounting and dismounting device isnot connected to the plug member, the shuttle 13 is positioned insidethe outer tube 12 in the proximal end portion (at the position shown inFIG. 1). In the embodiment shown in FIG. 1, a bolt 18 which passesthrough a through hole provided in the center of the cap 14 is screwedinto the shuttle 13, and the shuttle 13 is positioned in the proximalend of the outer tube 12 by adjusting the amount of threaded engagementof the bolt.

A plug member 11 of this embodiment is constituted as described above.Next, a plug member mounting and dismounting device 21 of thisembodiment will be explained.

A plug member 11 of this embodiment is automatically mounted anddismounted in the end of an oil country tubular good P by the plugmember mounting and dismounting device 21 according to the presentinvention shown in FIG. 2 and FIG. 3. The plug member mounting anddismounting device 21 comprises a tubular holding body 22, a rod 23, andmoving means 24 and 25 for independently moving the tubular holding body22 and the rod 23.

The tubular holding body 22 has an outer diameter which is slightlysmaller than the inner diameter of the outer tube 12 of the plug member11. It is inserted into the interior of the outer tube 12 of the plugmember 11 through the proximal end of the outer tube 12, and it can befreely moved in the interior of the outer tube 12 in the axial directionof the outer tube 12 by a moving means such as an actuator 24 in orderto support the plug member 11 by so-called cantilever supporting.

Four (for example) ball-receiving holes 22 a are provided inpredetermined locations of the tubular holding body 22, and a ball 26fits into each of these ball-receiving holes 22 a. The balls 26 havedimensions which allow them to be able to engage with thecircumferential groove 12 a provided in the inner peripheral surface ofthe outer tube 12. The balls 26 are housed in the ball-receiving holes22 a so as not to protrude outwards from the outer peripheral surface ofthe tubular holding body 22.

In the embodiment shown in FIG. 2, a conical cap 22 b which can fit intothe positioning recess 13 a provided in the above-described shuttle 13is attached to the tip (distal end) of the tubular holding body 22. Itensures positioning of the tubular holding body 22 with respect to theplug member 11.

The rod 23 is disposed inside the tubular holding body 22. The rod 23can be moved inside the tubular holding body 22 with respect to thetubular holding body 22 in its axial direction by a moving means such asan actuator 25. The distal end portion 23 a of the rod 23 has a conicalshape with an outer diameter which decreases from the proximal endtowards the distal end.

First, the tubular holding body 22 is moved with respect to the outertube 12 by operating an actuator 24 until the ball-receiving holes 22 aprovided in the tubular holding body 22 are aligned with thecircumferential groove 12 a provided in the outer tube 12. Next, the rod23 is moved with respect to the tubular holding body 22 which is movedand stopped as described above by operating an actuator 25 until theconical end portion 23 a of the rod 23 contacts the balls 26. As aresult, the balls 26 are made to protrude outwards from the outerperipheral surface of the tubular holding body 22. This causes the balls26 to engage with the circumferential groove 12 a, whereby the tubularholding body 22 and the outer tube 12 are connected to each other.

With the tubular holding body 22 and the outer tube 12 connected in thismanner, the rod 23 is moved backwards with respect to the tubularholding body 22 to move the conical end portion 23 a of the rod 23 awayfrom the balls 26, and the balls 26 are caused to fit into theball-receiving holes 22 a, thereby releasing the connection between thetubular holding body 22 and the outer tube 12.

As shown in FIG. 3 and FIG. 4, in this embodiment, a stopper 27 isdisposed forward of the plug member 11 having the outer tube 12connected to the tubular holding body 22. By abutting thereon the endsurface of an oil country tubular good P in which the plug member 11 isto be mounted, the stopper 27 simultaneously carries out alignment ofthe plug member 11 and the oil country tubular good P and mounting(placement) of the plug member 11 with respect to the oil countrytubular good P. As shown in FIG. 4, the stopper 27 has the shape of adiamond in which adjoining vertices have different angles and in whichthe corners are rounded so that alignment (axial alignment) of an oilcountry tubular good P and the tubular holding body 22 can be carriedout even when there is deviation of the center at the end of the oilcountry tubular good P from the center of the tubular holding body 22due to bending or the like of the tubular good P.

The stopper 27 is supported by an actuator 28. The cycle time requiredfor positioning of an oil country tubular good P at the time of mountingof a plug member 11 can be further decreased if the actuator 28 isoperated to position the stopper 27 in a predetermined position.

29 a-29 d in FIG. 3 and FIG. 4 are shock absorbers which support thestopper 27. They absorb shocks when an oil country tubular good Pstrikes the stopper 27 at the time of positioning of the oil countrytubular good P.

In the prior art with an apparatus such as a lathe including a plugmember mounting and dismounting device, in a preliminary step before aplug member is inserted into a long pipe, the long pipe is firsttransported in its lengthwise direction into the plug member mountingand dismounting device, and then after the pipe is positioned in itslengthwise direction, the plug member is mounted in the pipe. At thistime, a positioning stopper has to be operated by a cylinder from adirection other than the direction of transport of the pipe (such asfrom above or below) due to the presence of the plug member mounting anddismounting device which is positioned to the rear of the stopper in thelengthwise direction of the pipe (on the opposite side from thedirection of transport of the pipe).

Accordingly, the length of operational movement of the cylinder isnecessarily long and hence considerable time is required for taking inand out of the stopper. Furthermore, at the time of positioning of thepipe, an external force acts on the stopper in a different directionfrom the direction of operation due to impact with the pipe, andpositional deviation of the stopper or equipment malfunctions frequentlyoccurred.

In contrast, in this embodiment, a stopper 27, which performspositioning of an oil country tubular good P in which a plug member 11is to be mounted on the end by causing it to abut on the end surface ofthe tubular good P, is disposed forward of the plug member 11 which isconnected to the tubular holding body 22 in a state combined with theplug member mounting and dismounting device 21. Therefore, the timerequired for taking in and out of the stopper 27 by a cylinder or thelike can be omitted. Furthermore, the stopper 27 is not moved in adirection other than the direction of transport of an oil countrytubular good P. Accordingly, an external force due to impact with an oilcountry tubular good P at the time of positioning does not act on thestopper 27, and it is difficult for malfunctions and the like of thestopper 27 to take place.

Next, mounting of a plug member 11 according to the present invention inan end of an oil country tubular good P by a plug member mounting anddismounting device 21 according to the present invention will beexplained.

First, after positioning of an oil country tubular good P is carriedout, the vicinity of the end of the oil country tubular good P issupported by a floating chuck or the like with the axis of the portionof the pipe end which is to undergo working aligned with the rotationalaxis of the main shaft of a lathe. As a result, the axes of the pipe andan inside plug are aligned. The plug member 11 and the plug membermounting and dismounting device 21 are connected as shown in FIG. 2 byinserting the tubular holding body 22 of the device 21 into the outertube 12 of the plug member 11 until the ball-receiving holes 22 a of thebody 22 are aligned with the circumferential groove 12 a of the outertube 12 and in that state, then inserting the rod 23 into the tubularholding body 22 as described above.

Then, the actuator 24 is operated to advance the plug member mountingand dismounting device 21 which is connected to the plug member 11 suchthat the plug member 11 is inserted into the end portion of the oilcountry tubular good P as shown in FIG. 2.

After the plug member 11 is inserted, the tubular holding body 22 andthe outer tube 12 are separated from each other by moving the rod 23backwards with respect to the tubular holding body 22, whereby theconnection between the plug member mounting and dismounting device 21and the plug member 11 is released. The actuator 24 is then operated tomove the plug member mounting and dismounting device 21 backwards whileleaving the plug member 11 inside the oil country tubular good P, andthe mounting and dismounting device is pulled out of the oil countrytubular good P. Then, thread cutting is carried out on a predeterminedportion of the oil country tubular good P.

After thread cutting is carried out in this manner, the plug member 11is pulled out of the end of the oil country tubular good P by carryingout the opposite of the above-described operation.

The plug member 11 of this embodiment is mounted and dismounted byholding the interior of the plug member 11. Therefore, the problem ofshavings produced by thread cutting becoming wrapped around the plugmember 11 is completely eliminated.

In this embodiment, the plug member mounting and dismounting device 21can carry out positioning of the oil country tubular good P and mountingand dismounting of the plug member 11 in the end of the oil countrytubular good P just by forwards and backwards movements withoutperforming rotational movement.

1. A plug member which is mounted inside an end portion of a pipe whichis to undergo thread cutting, characterized by comprising an outer tubehaving a proximal end and a distal end a shuttle which is installed soas to be able to reciprocate inside the outer tube between the proximalend and the distal end, a cap which is mounted on the distal end of theouter tube to close off the opening of the distal end, and a shuttlebiasing spring having one end secured to the cap and the other endsecured to the shuttle, wherein the outer tube has a seal member whichis provided on its outer peripheral surface and which forms a sealagainst the pipe, and a circumferential groove which is formed in theinner peripheral surface of the tube in the proximal end portion, theshuttle is disposed in a predetermined position inside the proximal endportion of the outer tube, and the shuttle biasing spring produces aspring pressing force on the shuttle towards the proximal end when theshuttle moves from the predetermined position towards the distal end. 2.A plug member as set forth in claim 1 characterized in that the shuttlehas a fitting portion for positioning formed on the end surface of theshuttle on the side of the proximal end.
 3. A plug member mounting anddismounting device for mounting a plug member as set forth in claim 1 ina pipe or removing it from a pipe, characterized by comprising a tubularholding body which is disposed inside the outer tube so as to be able tomove with respect to the outer tube in the axial direction of the outertube, a rod which has a distal end portion with a conical shape whichdecreases in outer diameter from its proximal end towards its distal endand which is disposed inside the tubular holding body so as to be ableto move with respect to the tubular holding body in the axial directionof the tubular holding body, and moving means for independently movingthe tubular holding body and the rod, wherein the tubular holding bodyhas ball-receiving holes in a predetermined position into which ballswhich can engage with the circumferential groove of the outer tube canfit so as not to protrude outwards from the outer peripheral surface ofthe tubular holding body, and when it is inserted into the outer tubethrough the proximal end of the tube, its distal end can contact the endsurface of the proximal end of the shuttle, and the rod can make theballs protrude outwards from the outer peripheral surface of the tubularholding body and engage with the circumferential groove to connect thetubular holding body and the outer tube by moving relative to thetubular holding body so as to contact its distal end portion with theballs, and it can release the connection between the tubular holdingbody and the outer tube by moving relative to the tubular holding bodyso as to retracting its distal end portion from the balls and let theballs fit into the ball-receiving holes.
 4. A plug member mounting anddismounting device as set forth in claim 3 characterized by having afitting portion which is formed on the distal end of the tubular holdingbody and which fits into a fitting portion for positioning formed on theend surface of the shuttle on the side of the proximal end.
 5. A plugmember mounting and dismounting device as set forth in claim 3characterized by further having a stopper which is installed forward ofthe plug member having the outer tube connected to the tubular holdingbody, the stopper performing, by abutting thereon the end surface of apipe in which the plug member is to be mounted, alignment of the plugmember and the pipe and mounting of the plug member with respect to thepipe simultaneously.
 6. A plug member mounting and dismounting devicefor mounting a plug member as set forth in claim 2 in a pipe or removingit from a pipe, characterized by comprising a tubular holding body whichis disposed inside the outer tube so as to be able to move with respectto the outer tube in the axial direction of the outer tube, a rod whichhas a distal end portion with a conical shape which decreases in outerdiameter from its proximal end towards its distal end and which isdisposed inside the tubular holding body so as to be able to move withrespect to the tubular holding body in the axial direction of thetubular holding body, and moving means for independently moving thetubular holding body and the rod, wherein the tubular holding body hasball-receiving holes in a predetermined position into which balls whichcan engage with the circumferential groove of the outer tube can fit soas not to protrude outwards from the outer peripheral surface of thetubular holding body, and when it is inserted into the outer tubethrough the proximal end of the tube, its distal end can contact the endsurface of the proximal end of the shuttle, and the rod can make theballs protrude outwards from the outer peripheral surface of the tubularholding body and engage with the circumferential groove to connect thetubular holding body and the outer tube by moving relative to thetubular holding body so as to contact its distal end portion with theballs, and it can release the connection between the tubular holdingbody and the outer tube by moving relative to the tubular holding bodyso as to retracting its distal end portion from the balls and let theballs fit into the ball-receiving holes.
 7. A plug member mounting anddismounting device as set forth in claim 4 characterized by furtherhaving a stopper which is installed forward of the plug member havingthe outer tube connected to the tubular holding body, the stopperperforming, by abutting thereon the end surface of a pipe in which theplug member is to be mounted, alignment of the plug member and the pipeand mounting of the plug member with respect to the pipe simultaneously.